In a plasma system, a radio frequency (RF) signal is generated by a generator. The signal is transferred to a plasma reactor to generate plasma within the plasma reactor. The plasma formed in the plasma reactor is used for a variety of applications, e.g., clean a wafer, deposit materials on the wafer, etch the wafer, etc.
It is desirable to control properties of the plasma to control the applications. For example, it is desirable to control plasma uniformity to achieve an etch rate. As another example, it is desirable to control power of the plasma to achieve a deposition rate.
To control a property, the property is measured using a sensor in the plasma system.
It is in this context that embodiments described in the present disclosure arise.